Inline skating | running endurance training | VO2max

On weekend mornings, running paths are often crowded with in-line skaters, annoying some runners but making others wonder whether members of the skating crowd are actually getting a better, more enjoyable workout than they are. After all, skaters move faster than most joggers, and the smiles on skaters' faces, contrasted with the countenances of agony exhibited by many runners, suggest that skating is a fun, alternative way to trim away pounds, fortify the heart, and bolster the leg muscles.

The low-impact nature of skating is also attractive to those runners whose sore knees or aching Achilles tendons need temporary relief from the heavy pounding of running. Injuries (defined as problems severe enough to limit training) strike about 60 per cent of runners each year, with most of these maladies being sore anatomical regions roughed up by chronic 'overuse'. The true rate of injury among in-line skaters is unknown, but surveys suggest that about 31,000 of the 13 million in-line skaters in the United States end up in the hospital each year with a skating-related injury, about a .24- per cent (read that point-24, or less than 1-per cent) malady rate.

Although average injury rate is probably lower in skaters than runners, the big difference is that catastrophic injuries seem to be much more common in the first group. While runners are suffering from sore spots, skaters are more likely to completely fracture an arm or wrist bone as the result of a fall. There have also been anecdotal reports of skaters suffering catastrophic tears of an anterior cruciate ligament (ACL), an injury which rarely plagues endurance runners.

Some initial research efforts have also suggested that attempting to get fit by in-line skating might be something of a catastrophe. Basically, these early reports have indicated that the heart-rate response to in-line skating is higher than it is to running. Such findings suggest that individuals wanting to get fit via skating might have to skate at unusually high heart rates.

To put it another way, when you go out for a nice running workout at about 75 per cent of max heart rate, you can reasonably expect your oxygen consumption rate to also be high. In fact, your oxygen usage should be approximately 65 per cent of your maximal aerobic capacity, or VO2max. For most runners, this intensity is high enough to raise aerobic fitness.

Things change when you skate. In fact, studies suggest that with a skating heart rate of 75 per cent of max, your oxygen consumption might settle in at a miserly 50 per cent of VO2max. Many exercise physiologists would contend that such a simpering oxygen-consumption rate is not high enough to boost overall aerobic fitness. The implication is that you might have to get skating heart rates up to 90 per cent of max and hold them there - something few skaters can do - in order to get fit.

So, does in-line skating really represent an excel-lent form of exercise? Is it really a good alternative activity for runners? Fortunately, new research carried out at the University of Massachusetts at Amherst helps to bring the physiological benefits of in-line skating into sharper focus.

At UMass, 35 moderately fit undergraduate exercise science students underwent nine weeks of training in either running or in-line skating, while seven control individuals remained sedentary. Neither the 16 individuals who ended up in the running group nor the 19 subjects in the skating group had systematically carried out running or skating training prior to the study. Runners worked out either outdoors or on an indoor Tartan track, while skaters trained at an indoor skating facility (a 115-metre oval) with a hardwood, polished surface.

Training was divided into two stages. During the first stage (weeks 1-4), workout length and intensity were gradually increased from 20 minutes per session at 80 per cent of max heart rate (MHR) to 40 minutes at 90 per cent of MHR. In the second stage (weeks 5-9), workouts alternated between long, high-intensity efforts (40 minutes at 85 per cent of MHR) and interval sessions. A typical interval workout included a 10-minute warm-up and then six three-minute intervals at above 90 per cent of MHR, with one- minute recoveries. Heart rates were recorded during each training session, and there were three workouts per week. Of course, the runners ran to achieve the target heart rates, and the skaters skated (there was no mixing of exercise modes).

And the results? During the nine-week programme, the control individuals failed to improve, but the in-line skaters raised their VO2max (measured while running, not skating) by 6.5 per cent and boosted their endurance, gauged while running on the treadmill at a high-quality speed, by 7 per cent, even though their training had consisted solely of in-line skating! In other words, the skate training had made the skaters better runners! There was a trend for the run-trained people to make bigger improvements in running capacity, compared to the skaters (9 per cent gain in VO2max, 14 per cent rise in time to exhaustion on the treadmill), but the differences were not statistically significant.

The skaters also upgraded VO2max and time to exhaustion while skating (measured on a special treadmill designed to accommodate in-line skating), but these improvements were only slightly greater than the gains they had made in running capacity. Specifically, the skaters lifted skating VO2max by 8.1 per cent and raised time to exhaustion while skating by 7.5 per cent, just a bit above the 6.5 uptick in running VO2max and the 7 per cent rise in running endurance. To put it another way, we can say that about 80 per cent (6.5/8.1) of the VO2max upgrade from skating was transferred directly over to running. In addition, approximately 93 per cent (7.0/7.5) of the upturn in endurance capacity was sent right over from skating to running. Those are impressive numbers!
The fine physiological gains associated with skating uncovered by the UMass team are in synch with the findings obtained by other researchers. For example, investigators at the University of Wisconsin-LaCrosse recently determined that skaters can attain rates of oxygen consumption high enough to boost fitness without too much trouble. The Wisconsin team also pegged calorie-burning rates in moderately fit individuals during in-line skating to be as high as 19 calories per minute, enough to trim away one-third of a pound of blubber in 61 minutes. You'd have to run about 10 miles in the same time frame to burn as many calories.

The bottom line? From the standpoint of fractured arm bones and lacerated knee ligaments, skating is riskier than running. And if you are an elite runner, it's doubtful that in-line skating sessions will have any direct impact on your fitness, although they could refresh you psychologically and give your legs a break (oops: sorry! We mean that skating could give sore legs a chance to recover).

However, if you're at a moderate level of fitness and you want to improve your aerobic capacity and endurance, you can make similar gains by in-line skating or running, and about 80 to 93 per cent of the gains you make from skating are transferred directly over to running. The truth is that when intensity, frequency, and training duration are matched, the physiological benefits of the two activities are pretty similar. That may be welcome news to runners who have been interested in giving skating a try - or who want to carry out some cross training on skates in order to give their running-related injuries a chance to mend.